1. Field of the Invention
This invention relates to an acoustic treatment panel that integrates a reinforcement for ensuring a connection with at least one other panel, aimed at reducing the untreated surface on the acoustic plane of an air intake of a nacelle.
2. Description of the Related Art
According to an embodiment illustrated in FIG. 1, a nacelle 10 comprises at least one pipe 12, a peripheral wall 14, and, at the front, an air intake that is delimited by a lip 16 that connects the pipe 12 and the peripheral wall 14.
In a known manner, the pipe 12 comprises a coating or panel 18 for acoustic treatment comprising, from the inside to the outside, a reflective layer 20, at least one alveolar structure 22, and at least one acoustically resistive structure 24 that forms the aerodynamic surface of the pipe 12. Advantageously, the lip 16 can also comprise a coating for acoustic treatment.
To reinforce the structure of the nacelle, a front frame 26 connects the pipe 12 and the peripheral wall 14, whereby the lip 16 is made integral with said front frame 26.
According to one embodiment, to ensure the connection between the panel that forms the lip 16 and the panel that forms the peripheral wall 14, the edges of said panels are flattened and then secured by any suitable means against a flange 28 of the front frame 26.
According to an embodiment that is illustrated in details in FIG. 2, at the junction zone of the pipe 12 and the lip 16, the front frame 26 comprises a flange 30 against which the wall forming the lip 16 is flattened. At this level, the reflective layer 20 and the acoustically resistive structure 24 have dimensions that are larger than those of the alveolar structure 22 so as to be convergent and then flattened against one another and secured against the inside surface of the lip that extends beyond the flange 30. In addition, a reinforcement 32 is provided to ensure the connection between, on the one hand, the two coupled layers 22 and 24, and, on the other hand, the front frame.
This configuration is not satisfactory for the following reasons:
Since the forces that pass through the reflective layer and through the acoustically resistive structure are not balanced, this creates a problem of unfolding at the junction zone with the lip and of delamination, whereby the different parts of the coating are made of composite materials for reasons of increasing weight.
According to another drawback, the terminal zone of the acoustic coating at which the reflective layer and the acoustically resistive structure are convergent is not treated on the acoustic plane. Consequently, this zone is combined with the superposition zones, on the one hand, of the lip and the front frame, and, on the other hand, of the lip and two coupled layers 22 and 24; this leads to a zone LO that is not treated on the important acoustic level.